ohair@286: /*
alanb@368:  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
ohair@286:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ohair@286:  *
ohair@286:  * This code is free software; you can redistribute it and/or modify it
ohair@286:  * under the terms of the GNU General Public License version 2 only, as
ohair@286:  * published by the Free Software Foundation.  Oracle designates this
ohair@286:  * particular file as subject to the "Classpath" exception as provided
ohair@286:  * by Oracle in the LICENSE file that accompanied this code.
ohair@286:  *
ohair@286:  * This code is distributed in the hope that it will be useful, but WITHOUT
ohair@286:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ohair@286:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ohair@286:  * version 2 for more details (a copy is included in the LICENSE file that
ohair@286:  * accompanied this code).
ohair@286:  *
ohair@286:  * You should have received a copy of the GNU General Public License version
ohair@286:  * 2 along with this work; if not, write to the Free Software Foundation,
ohair@286:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ohair@286:  *
ohair@286:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
ohair@286:  * or visit www.oracle.com if you need additional information or have any
ohair@286:  * questions.
ohair@286:  */
ohair@286: 
ohair@286: package com.sun.xml.internal.ws.util;
ohair@286: 
ohair@286: import com.sun.xml.internal.ws.api.pipe.Tube;
ohair@286: import com.sun.xml.internal.ws.api.pipe.TubeCloner;
ohair@286: 
ohair@286: import javax.xml.bind.JAXBContext;
ohair@286: import javax.xml.bind.JAXBException;
ohair@286: import java.util.concurrent.ConcurrentLinkedQueue;
ohair@286: import java.lang.ref.WeakReference;
ohair@286: 
ohair@286: /**
ohair@286:  * General-purpose object pool.
ohair@286:  *
ohair@286:  * <p>
ohair@286:  * In many parts of the runtime, we need to pool instances of objects that
ohair@286:  * are expensive to create (such as JAXB objects, StAX parsers, {@link Tube} instances.)
ohair@286:  *
ohair@286:  * <p>
ohair@286:  * This class provides a default implementation of such a pool.
ohair@286:  *
ohair@286:  * TODO: improve the implementation
ohair@286:  *
ohair@286:  * @author Kohsuke Kawaguchi
ohair@286:  */
ohair@286: public abstract class Pool<T> {
ohair@286: 
ohair@286:     // volatile since multiple threads may access queue reference
ohair@286:     private volatile WeakReference<ConcurrentLinkedQueue<T>> queue;
ohair@286: 
ohair@286:     /**
ohair@286:      * Gets a new object from the pool.
ohair@286:      *
ohair@286:      * <p>
ohair@286:      * If no object is available in the pool, this method creates a new one.
ohair@286:      *
ohair@286:      * @return
ohair@286:      *      always non-null.
ohair@286:      */
ohair@286:     public final T take() {
ohair@286:         T t = getQueue().poll();
ohair@286:         if(t==null)
ohair@286:             return create();
ohair@286:         return t;
ohair@286:     }
ohair@286: 
ohair@286:     private ConcurrentLinkedQueue<T> getQueue() {
ohair@286:         WeakReference<ConcurrentLinkedQueue<T>> q = queue;
ohair@286:         if (q != null) {
ohair@286:             ConcurrentLinkedQueue<T> d = q.get();
ohair@286:             if (d != null)
ohair@286:                 return d;
ohair@286:         }
ohair@286: 
ohair@286:         // overwrite the queue
ohair@286:         ConcurrentLinkedQueue<T> d = new ConcurrentLinkedQueue<T>();
ohair@286:         queue = new WeakReference<ConcurrentLinkedQueue<T>>(d);
ohair@286: 
ohair@286:         return d;
ohair@286:     }
ohair@286: 
ohair@286:     /**
ohair@286:      * Returns an object back to the pool.
ohair@286:      */
ohair@286:     public final void recycle(T t) {
ohair@286:         getQueue().offer(t);
ohair@286:     }
ohair@286: 
ohair@286:     /**
ohair@286:      * Creates a new instance of object.
ohair@286:      *
ohair@286:      * <p>
ohair@286:      * This method is used when someone wants to
ohair@286:      * {@link #take() take} an object from an empty pool.
ohair@286:      *
ohair@286:      * <p>
ohair@286:      * Also note that multiple threads may call this method
ohair@286:      * concurrently.
ohair@286:      */
ohair@286:     protected abstract T create();
ohair@286: 
ohair@286: 
ohair@286:     /**
ohair@286:      * JAXB {@link javax.xml.bind.Marshaller} pool.
ohair@286:      */
ohair@286:     public static final class Marshaller extends Pool<javax.xml.bind.Marshaller> {
ohair@286:         private final JAXBContext context;
ohair@286: 
ohair@286:         public Marshaller(JAXBContext context) {
ohair@286:             this.context = context;
ohair@286:         }
ohair@286: 
alanb@368:         @Override
ohair@286:         protected javax.xml.bind.Marshaller create() {
ohair@286:             try {
ohair@286:                 return context.createMarshaller();
ohair@286:             } catch (JAXBException e) {
ohair@286:                 // impossible
ohair@286:                 throw new AssertionError(e);
ohair@286:             }
ohair@286:         }
ohair@286:     }
ohair@286: 
ohair@286:     /**
ohair@286:      * JAXB {@link javax.xml.bind.Marshaller} pool.
ohair@286:      */
ohair@286:     public static final class Unmarshaller extends Pool<javax.xml.bind.Unmarshaller> {
ohair@286:         private final JAXBContext context;
ohair@286: 
ohair@286:         public Unmarshaller(JAXBContext context) {
ohair@286:             this.context = context;
ohair@286:         }
ohair@286: 
alanb@368:         @Override
ohair@286:         protected javax.xml.bind.Unmarshaller create() {
ohair@286:             try {
ohair@286:                 return context.createUnmarshaller();
ohair@286:             } catch (JAXBException e) {
ohair@286:                 // impossible
ohair@286:                 throw new AssertionError(e);
ohair@286:             }
ohair@286:         }
ohair@286:     }
ohair@286: 
ohair@286:     /**
ohair@286:      * {@link Tube} pool.
ohair@286:      */
ohair@286:     public static final class TubePool extends Pool<Tube> {
ohair@286:         private final Tube master;
ohair@286: 
ohair@286:         public TubePool(Tube master) {
ohair@286:             this.master = master;
ohair@286:             recycle(master);    // we'll use master as a part of the pool, too.
ohair@286:         }
ohair@286: 
alanb@368:         @Override
ohair@286:         protected Tube create() {
ohair@286:             return TubeCloner.clone(master);
ohair@286:         }
alanb@368: 
alanb@368:         /**
alanb@368:          *
alanb@368:          * @return master tubeline from pool
alanb@368:          * @deprecated Expected to be used in rare cases where access to master
alanb@368:          * tubeline is required and safe, such as Stub.close()."
alanb@368:          */
alanb@368:         @Deprecated()
alanb@368:         public final Tube takeMaster() {
alanb@368:             return master;
alanb@368:         }
alanb@368: 
ohair@286:     }
ohair@286: }